Related Experiment Video
Updated: Aug 4, 2026
12:24
Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout (Salvelinus namaycush) from Its Prey
Published on: August 29, 2014
Prey fish returned to Forster's tern colonies suggest spatial and temporal differences in fish composition and
Sarah H Peterson1, Joshua T Ackerman1, Collin A Eagles-Smith2
1Dixon Field Station, Western Ecological Research Center, U.S. Geological Survey, Dixon, California, United States of America.
Plos One
|March 16, 2018
Summary
Forster
Area of Science:
- Ecological foraging dynamics
- Avian dietary studies
- Fisheries and aquatic ecosystem monitoring
Background:
- Predator diets reflect environmental conditions and prey availability.
- Forster's terns (Sterna forsteri) are central place foragers, providing insights into local prey resources.
- Understanding prey composition is crucial for assessing ecosystem health.
Purpose of the Study:
- To analyze changes in Forster's tern prey species composition over an 11-year period.
- To compare prey species diversity and abundance across different breeding colonies.
- To infer environmental shifts based on predator foraging patterns.
Main Methods:
- Collected and identified approximately 10,000 prey fish from 17 Forster's tern colonies.
- Analyzed prey species relative abundance and dry mass composition.
- Compared species composition across colonies sampled over multiple years (≥ 4 years).
Main Results:
- Prey species composition varied significantly between colonies, indicating spatial differences in fish communities.
- Mississippi silverside and topsmelt silverside were dominant prey items.
- Trends showed an increase in silverside abundance and a decrease in three-spined stickleback and longjaw mudsucker over time at some colonies.
Conclusions:
- Shifts in Forster's tern diet suggest changes in the relative availability of key fish species in South San Francisco Bay.
- Habitat alteration may be a contributing factor to observed changes in prey fish populations.
- Forster's tern foraging data serves as a valuable indicator of aquatic ecosystem changes.
Related Concept Videos
01:06Fixed Action Patterns
A fixed action pattern (FAP) is a specific, hard-wired sequence of behaviors that occurs in response to an external stimulus, called a sign stimulus. The behavior is “fixed” because it is essentially unchangeable—proceeding similarly across individuals of a species every time it occurs.
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
00:51Energy Budgets and Reproductive Strategies
Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species reproduce only once in their lifetime, often investing most available resources into that single reproductive event. Iteroparous species, by contrast, reproduce multiple times over their lifetimes, typically allocating fewer resources to any single...
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.